Showing papers on "Permeability (earth sciences) published in 2016"
TL;DR: In this article, the pore-throat size distribution in a suite of tight reservoir from the fourth member of the Lower Cretaceous Quantou Formation (K 1 q 4 ) in the southern Songliao Basin, China has been investigated under laboratory pressure conditions.
200 citations
TL;DR: In this article, a unified model of nanopore gas transport in shale gas reservoirs is presented, which considers the gas transport mechanisms of viscous flow, Knudsen diffusion, surface diffusion, adsorption and desorption.
199 citations
TL;DR: In this paper, the anisotropic permeability in three directions of three cubic shale samples from Lower Silurian Longmaxi Formation in southeastern Sichuan Basin, China was investigated.
152 citations
TL;DR: In this article, the authors provide an overview of the recent developments in the pore structure characterization of tight gas sandstones, permeability measurement techniques, and enhanced tight gas recovery techniques.
152 citations
TL;DR: In this paper, the effect of pore-scale heterogeneity on non-Darcy flow behavior is investigated by means of direct flow simulations on 3D images of a beadpack, Bentheimer sandstone and Estaillades carbonate.
143 citations
TL;DR: In this article, the authors used a two-dimensional model that considers flow in parallel layers to determine the porosity of the tensile fractures in low-porosity andesites.
140 citations
TL;DR: In this paper, the impact of sub-resolution porosity on the macroscopic (Darcy scale) flow properties of the rock has been analyzed using high-resolution X-ray microtomography.
Abstract: There is growing interest in using advanced imaging techniques to describe the complex pore-space of natural rocks at resolutions that allow for quantitative assessment of the flow and transport behaviors in these complex media. Here, we focus on representations of the complex pore-space obtained from X-ray microtomography and the subsequent use of such ‘pore-scale’ representations to characterize the overall porosity and permeability of the rock sample. Specifically, we analyze the impact of sub-resolution porosity on the macroscopic (Darcy scale) flow properties of the rock. The pore structure of a rock sample is obtained using high-resolution X-ray microtomography $$(3.16^3\,{\upmu } \hbox {m}^{3}/\hbox {voxel})$$
. Image analysis of the Berea sandstone sample indicates that about 2 % of the connected porosity lies below the resolution of the instrument. We employ a Darcy–Brinkman approach, in which a Darcy model is used for the sub-resolution porosity, and the Stokes equation is used to describe the flow in the fully resolved pore-space. We compare the Darcy–Brinkman numerical simulations with core flooding experiments, and we show that proper interpretation of the sub-resolution porosity can be essential in characterizing the overall permeability of natural porous media.
131 citations
TL;DR: In this article, the authors proposed a model that does away with the shortcomings of the Maxwell slip condition and uses readily available Langmuir sorption data to determine slip coefficient for gas flow, and includes the higher-order slip effects on gas flow.
131 citations
TL;DR: In this paper, the authors provide an overview of the challenges associated with evaluating key reservoir and hydraulic fracture properties and discuss recent advances in the area of shale gas reservoir and fracture characterization.
128 citations
TL;DR: In this article, the authors studied the factors that control reservoir heterogeneity and the heterogeneity of oil accumulation in tight oil sandstones in the Upper Triassic Yanchang Formation in the Ordos Basin.
127 citations
TL;DR: In this article, the porosities of hydrate-bearing porous media formed by different-size particles, as calculated by both the pore network models and the volumetric method, are in agreement.
TL;DR: In this paper, the main formation damage mechanisms during shale gas reservoir exploitation, including the physical and chemical damage, are discussed in detail, and the systematic evaluation method of formation damage, heat treatment and working fluid loss control, as three further research directions for formation damage control and removal are proposed for the efficient development of shale gas reservoirs.
TL;DR: In this paper, the authors investigated the deformation, failure and permeability of coal-bearing strata during longwall mining and their influences on the construction of groundwater reservoirs at the Daliuta coal mine.
TL;DR: In this paper, the combined techniques of micro-focus X-ray computed tomography (CT) and pore-network model simulation were used to identify proper values for those key parameters, such as gas entry pressure, residual water saturation, and curve fitting values.
Abstract: The water retention curve and relative permeability are critical to predict gas and water production from hydrate-bearing sediments. However, values for key parameters that characterize gas and water flows during hydrate dissociation have not been identified due to experimental challenges. This study utilizes the combined techniques of micro-focus X-ray computed tomography (CT) and pore-network model simulation to identify proper values for those key parameters, such as gas entry pressure, residual water saturation, and curve fitting values. Hydrates with various saturation and morphology are realized in the pore-network that was extracted from micron-resolution CT images of sediments recovered from the hydrate deposit at the Mallik site, and then the processes of gas invasion, hydrate dissociation, gas expansion, and gas and water permeability are simulated. Results show that greater hydrate saturation in sediments lead to higher gas entry pressure, higher residual water saturation, and steeper water retention curve. An increase in hydrate saturation decreases gas permeability but has marginal effects on water permeability in sediments with uniformly distributed hydrate. Hydrate morphology has more significant impacts than hydrate saturation on relative permeability. Sediments with heterogeneously distributed hydrate tend to result in lower residual water saturation and higher gas and water permeability. In this sense, the Brooks-Corey model that uses two fitting parameters individually for gas and water permeability properly capture the effect of hydrate saturation and morphology on gas and water flows in hydrate-bearing sediments.
TL;DR: A review of previous works that have focused on the estimation of equivalent permeability of two-dimensional (2D) discrete fracture networks (DFNs) considering the influences of geometric properties of fractured rock masses is provided in this article.
Abstract: Fracture networks play a more significant role in conducting fluid flow and solute transport in fractured rock masses, comparing with that of the rock matrix. Accurate estimation of the permeability of fracture networks would help researchers and engineers better assess the performance of projects associated with fluid flow in fractured rock masses. This study provides a review of previous works that have focused on the estimation of equivalent permeability of two-dimensional (2-D) discrete fracture networks (DFNs) considering the influences of geometric properties of fractured rock masses. Mathematical expressions for the effects of nine important parameters that significantly impact on the equivalent permeability of DFNs are summarized, including (1) fracture-length distribution, (2) aperture distribution, (3) fracture surface roughness, (4) fracture dead-end, (5) number of intersections, (6) hydraulic gradient, (7) boundary stress, (8) anisotropy, and (9) scale. Recent developments of 3-D fracture networks are briefly reviewed to underline the importance of utilizing 3-D models in future research.
TL;DR: In this article, a set of partial differential equations are derived to define various flow and deformation processes: (1) mechanical equilibrium equation that defines the shale deformation; (2) gas flow in the kerogen system of matrix; (3) gas flows in the inorganic system of matrices; and (4) hydraulic fracture system.
TL;DR: Pervious concrete (PC) mixtures were designed and prepared to measure and study permeability characteristics at varying head levels using a falling head permeameter, and a total of 1092 readings were used to study the permeability properties of eighteen PC mixtures whose porosity was in the range of 15-37%, and permeability in the realm of 0.076-3.5 cm/s as mentioned in this paper.
TL;DR: In this paper, the influence of imbibition on the matrix permeability, micro-fracture permeability and fracture permeability was investigated, and the experimental results showed that the imbibed fracturing fluid will damage and seriously reduce the matrix of the shale sample.
TL;DR: In this article, the authors measured the coal properties required to apply models for the behavior of the absolute reservoir permeability during gas production and used the measured properties to predict permeability behavior with pressure drawdown.
TL;DR: In this article, the effectiveness of supercritical carbon dioxide (ScCO2)-based reservoir fracturing associated with CO2enhanced shale gas recovery is explored to reduce water utilization in shale gas production and has the potential for CO2 sequestration.
TL;DR: In this paper, the effect of Alnus incana roots on soil aggregate stability and surface and volume permeability was investigated in four different growing periods (1, 2, 4 and 8 months).
Abstract: Assessing the joint development of vegetation cover and soil properties is crucial to evaluate the efficiency of soil bioengineering techniques, especially during the most critical initial phase of vegetation colonization. We set up a laboratory experiment to quantify and disentangle the effect of Alnus incana roots on soil permeability and aggregate stability. Plants were grown in pots in a climate chamber for four different growing periods (1, 2, 4 and 8 months). Pots were filled with a soil coming from a moraine of a landslide area in Central Switzerland. After each growing period, surface permeability, soil volume permeability and soil aggregate stability were measured together with the development of the root systems. Our results show that alder roots significantly improve both surface and whole soil volume permeability already after 2 months of growth. Nevertheless, an increase in root length density does not necessarily correspond to an increase in permeability. We could set as a threshold a root length density of 0.1 cm/cm3 until which an increase in root development corresponds to an increase in soil permeability, whereas after this threshold we observed a decrease in soil permeability. A significant increase in soil aggregate stability could be observed only with a root length density of 2 cm/cm3. No obvious correlation between soil permeability and aggregate stability could be found. Future work should validate these laboratory results with field data. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors introduced a lithofacies classification for shale based on rock mineral composition, and analyzed the key factors that affect shale gas content and storage of shale gas were analyzed.
TL;DR: In this paper, a study of slip flow in shale gas reservoirs is presented, where the slip boundary conditions were used to obtain the slip coefficients and tangential momentum accommodation coefficient in porous media from the experimental data.
TL;DR: In this article, a fully coupled thermal-hydraulic-mechanical model (THM) including coal deformation, gas seepage, water seepages, and thermal transport governing equations is developed and solved using the finite element (FE) method.
TL;DR: In this paper, the authors developed a three-dimensional transient model, which describes the multi-physical coupling of thermal (T), hydraulic (H), and mechanical (M) processes during heat extraction of enhanced geothermal systems.
TL;DR: In this paper, the effect of fine migration on water and oil relative permeability was investigated, and the modified Welge-JBN method was used to determine the phase relative percolation.
TL;DR: In this article, the authors measured the methane diffusion coefficient for pulverized San Juan sub-bituminous and Pittsburgh bituminous coal samples using the classic unipore model and particle method.
Abstract: Gas diffusion in coal is critical for the prediction of coalbed methane (CBM) production, especially for the late-stage CBM reservoir when both gas pressure and permeability are relative low. Using only Darcy permeability to evaluate the quality of gas transport might not be effective. Diffusive flow can be the dominant flow at low reservoir pressures. In this work, the methane diffusion coefficient was measured for pulverized San Juan sub-bituminous and Pittsburgh bituminous coal samples using the classic unipore model and particle method. The diffusion coefficient results showed a negative correlation with pressure, as reported previously. The significance of diffusion flow is strongly related to the rate of the methane ad-/desorption process, more severely in the low pressure range [<2 MPa (280 psi)]. The measured diffusion coefficient can be converted to the equivalent permeability. This equivalent permeability, termed diffusive permeability, can be considered as the contribution of diffusion flow, in...
TL;DR: In this paper, an analytical coal permeability model and its five forms under the corresponding specific boundary conditions were developed, and four of them were validated by matching the corresponding field data or experimental data.
TL;DR: In this paper, the effect of coal plug swelling due to brine adsorption on the coal micro-structure is investigated, and how this microstructural change impacts on the porosity and porosity characteristics of the coal.
TL;DR: In this article, a model for water permeability reduction in hydrate-bearing sediments is presented by considering capillary effect of hydrate nucleation in both grain-coating and pore-filling cases.
Abstract: A model for water permeability reduction in hydrate-bearing sediments is presented by considering capillary effect in hydrate nucleation. Both grain-coating and pore-filling cases are considered. The model is developed from a series of lattice Boltzmann flow simulations. Results show that the permeability decreases quasi-linearly with increasing hydrate saturation during grain-coating nucleation and that the permeability tends to be higher than predicted by previous analytical models in which capillarity is not taken into account. The permeability follows unique reduction curve and is not so sensitive to initial sediment bulk density and grain size distribution. Simulations further show that there is a transition zone at Shyd = 0.3 ~ 0.4 where permeability reduction trend switches from grain-coating model to pore-filling model. Analyses of tortuosity and surface area confirm that the permeability reduction mechanisms result from pore-channel blocking in grain-coating case and pore-size reduction in pore-filling case.